Allen-Bradley 1784-KTX Reference Manual page 25

Establish Test Mode
1.
2.
Run Diagnostic
Verify that data can be properly written to and read from the entire
dual-port memory.
1.
2.
3.
4.
Allen-Bradley Parts
Write to key 0, address 805, with a 0xAA, and to key 1, address 807,
with a 0x55.
Verify that the key has been properly written by performing a 16-bit
read of address 800.
The value returned should be 0xFFAA. The 0xAA in the return
value will be proper because the system initiates a 16-bit read and
uses the data from the low byte lane when M16 is not asserted by the
ASIC.
The system will then come back to the card with an 8-bit read of the
high byte (assuming the card to be 8-bit because M16 was not
asserted) and the ASIC will not respond to the 8-bit read of the high
byte of the key. Thus the returned data for the odd byte will be the
pulled-up ISA bus, or 0xFF.
If a value other than 0xFF is returned in the high byte of the word,
then test mode has not been properly established.
Fill the dual port with these values, one at a time, and verify that the
proper values are returned:
a. 0xFF
b. 0x00
c. 0x55
d. 0xAA
Start at the beginning of the dual port (base address, offset 0) and
perform 16-bit writes of the value 'count' to memory, incrementing
'count' and the word address until the dual port is full.
Verify that the dual port contains word values incrementing from
0x0000 to 0x03FF.
Report pass or fail to the user.
Chapter 2
Start up and Shutdown
2-9